This is only relevant for Linux and macOS and can be safely ignored if running
Elasticsearch on Windows. On Windows that JVM uses an
API
limited only by available resources.

Elasticsearch uses a lot of file descriptors or file handles. Running out of
file descriptors can be disastrous and will most probably lead to data loss.
Make sure to increase the limit on the number of open files descriptors for
the user running Elasticsearch to 65,536 or higher.